A few years ago, backstage at a conference, I spotted a blind woman using her phone. The phone was speaking everything her finger touched on the screen, allowing her to tear through her apps. My jaw hit the floor. After years of practice, she had cranked the voice’s speed so high, I couldn’t understand a word it was saying.

And here’s the kicker: She could do all of this with the screen turned off. Her phone’s battery lasted forever.